Hydrogenated amorphous carbon (a-C:H) and ultra-nanocrystalline diamond/amorphous carbon (UNCD/a-C:H) composite films are considered as excellent candidates for use as biocompatible coatings on biomedical implants. The aim of this work is a comparative study of the wetting behaviour and protein adsorption on a-C:H and UNCD/a-C:H films prepared by microwave plasma chemical vapour deposition (MWCVD) under different process conditions. All films were characterized by a variety of methods: their morphology by scanning electron microscopy (SEM), the topography by atomic force microscopy (AFM), the chemical bonding structure by Raman spectroscopy. SEM revealed that the a-C:H films possess a columnlike morphology, while the UNCD/a-C:H surfaces are composed of structures with diameters of several hundreds nanometers, which themselves have a sub-structure. All films under investigation were rather smooth with rms roughnesses down to 2 nm for a-C:H and to 12 nm for UNCD/a-C:H, as shown by AFM topography analyses. The wettability of the coatings was investigated by contact angle measurements, from which the surface energy was determined. An inverted Enzyme-Linked ImmunoSorbent Assay (ELISA) was performed in order to investigate the protein adsorption on the surfaces of the materials. The proteins studied were albumin and fibrinogen which are known to affect the blood compatibility. The albumin/fibrinogen ratio, which can be used to evaluate the tendency of thrombus formation, was calculated and compared for all samples under investigation.
- protein adsorption